Neurovascular aspiration catheter with tip shape

Abstract

The aspiration catheter comprises an elongated flexible tubular body having a sidewall and a distal tip. A helical coil is embedded in the sidewall and extends from a proximal end of the catheter to a location proximally offset from the distal tip. A reinforcing fiber is embedded longitudinally in the sidewall beginning at a location proximally offset from the distal tip and extending at least 10 cm proximally. The distal tip has a shaped edge to aid in passing the tip of the catheter over a prong of a bifurcation.

Description

[Technical field]

[0001] The present invention relates to a neurovascular aspiration catheter having a tip geometry that can be used to perform direct aspiration thrombectomy in patients with large vessel occlusions.

[0002] Large vessel occlusion in the cerebral vasculature causes ischemic stroke. Stroke affects more than 800,000 Americans each year, yet remains a largely unaddressed problem. The number of deaths from stroke continues to rise. Treatment techniques have improved significantly as thrombectomy designs have become more sophisticated, but the need for improved efficacy and efficiency remains.

[0003] In recent years, several clinical trials have established mechanical thrombectomy using a stent retriever as the gold standard treatment option for patients with large vessel occlusion. More recent data suggest that direct aspiration using a large-bore catheter is a valid alternative to stent retriever-based methods. In direct aspiration thrombectomy, a suction catheter with a large lumen (large bore) is used to aspirate and remove the thrombus. If aspiration is not successful, the large-bore aspiration catheter can be used as a platform to deliver a stent retriever or other devices.

[0004] Conventional large bore suction catheters suffer from several drawbacks.

[0005] First, nearly all large-bore aspiration catheters currently on the market feature the same straight-tip design (flat edge perpendicular to the central axis of the catheter). A common problem with large-bore aspiration catheters is the inability to maneuver the catheter through complex and tortuous neurovasculature to reach the site of occlusion. One particular challenge during manipulation is to allow the catheter tip to pass certain junctions within the intracranial arteries, such as the origin of the ophthalmic artery. The catheter tip can get stuck or stuck at such locations. This phenomenon is known as the "ledge effect." This is best illustrated in Figures 1A and 1B. Figure 1A shows the distal end of an aspiration catheter C being traced over a guidewire G and approaching a ledge L, while Figure 1B shows that the distal tip of catheter C has become stuck at ledge L. The straight tip profile creates a challenging situation when tracing over the guidewire, with approximately half or more of the tip's cross section hitting ledge L and leaning into the bifurcation. This occurs because of a large difference between the guidewire diameter and the inner diameter of the catheter, forcing the guidewire against the sidewall of the catheter and away from the centerline. Further pushing or pulling of the catheter C and the guidewire is often insufficient to alleviate the situation. Thus, large-bore catheters in a straight-tip configuration may not be effective at passing through these locations because once the distal tip hits the protuberance, it becomes difficult to advance the catheter forward and out of the protuberance.

[0006] Second, one of the existing risks of current aspiration catheters is tensile breakage at the distal tip of the catheter. As players in the neurovascular field seek to increase the size of aspiration catheters, a major design challenge facing companies is to keep the catheter soft enough to navigate the tortuous anatomy (large twists and turns) of the cerebral arteries, despite the aspiration catheter becoming significantly larger and therefore containing a greater total amount of material. In pursuit of this, companies are increasingly using softer and weaker polymer materials in the design of the distal portion of the catheter, resulting in the sacrifice of tensile strength. In an effort to make catheters more flexible and easier to navigate, some designs have lower tensile strength at the distal end of the catheter. These catheters with lower tensile strength are at higher risk of breakage or material separation during use, which can lead to clinical harm and adverse events.

[0007] Additionally, larger catheters have a larger contact area with the vessel wall, increasing frictional forces. This, coupled with a larger diameter in the user's hand, can lead to the perception of a more robust product that can withstand greater forces. That is, physicians tend to apply more force when pulling on a larger catheter than they would on a smaller catheter if the catheter becomes stuck.

[0008] The combination of these factors results in low tensile strength for various aspiration catheter products, leading to catheter breakage, undesirable outcomes, and adverse events during field use.

[0009] Therefore, there remains a need for a large bore aspiration catheter that overcomes these drawbacks. Summary of the Invention

[0010] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to provide a large bore aspiration catheter having a tip shaped to improve ease of navigation, particularly through vascular protuberances.

[0011] Another object of the present invention is to provide a large bore aspiration catheter with improved distal tensile strength that results in fewer procedures with adverse events due to tensile failure.

[0012] In accordance with the objects of the present invention, an aspiration catheter is provided having an elongated flexible tubular body having a sidewall and a distal tip. A helical coil is embedded in the sidewall and extends from a proximal end of the catheter to a location proximally offset from the distal tip. A reinforcing fiber is embedded longitudinally in the sidewall beginning at a location proximally offset from the distal tip and extending at least 10 cm proximally. The distal tip has a shaped lip that assists in passing the tip of the catheter over a prong of a bifurcation.

[0013] In one embodiment, the distal tip has scalloped edges that transition smoothly between peaks and valleys in the circumferential direction to form a taper. [Brief description of the drawings]

[0014] [Figure 1] 1A and 1B show how the distal tip of a conventional aspiration catheter can become wedged or stuck at a junction in an intracranial artery. [Diagram 2] FIG. 1 is a perspective view of an aspiration catheter according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a side view of the catheter of FIG. 2. [Figure 4] FIG. 3 is a top view of the catheter of FIG. 2. [Diagram 5] FIG. 4 is a cross-sectional side view of the distal region of the catheter of FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. 5. [Figure 7] 7A and 7B are two different isometric views of the distal port of the catheter of FIG. [Figure 8] 8A-8C show how the distal wavy tip of the catheter of FIG. 2 assists the catheter in passing through a protrusion L of a vessel bifurcation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The following detailed description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims.

[0016] 2-6 show one embodiment of the inventive aspiration catheter 100 having a distal wavy tip. As shown in FIGS. 2-6, the aspiration catheter 100 has a handle assembly 102 at a proximal end 104 and an elongated flexible tubular body 106 extending from the handle assembly 102 to a distal end 108. At the distal end 108 is a novel distal wavy tip 110. The tubular body 106 has a sidewall 114 with an optional inner liner 128 that defines a central cavity (central lumen) 116, the central cavity 116 having a longitudinal axis. An outer jacket 130 defines an outer layer or shell of the sidewall 114. The sidewall 114 itself is comprised of the inner liner 128 and the outer jacket 130. The sidewall 114 may also be comprised solely of the jacket material (i.e., the liner is optional). In that case, the jacket may define both the inner and outer surfaces of the sidewall 114.

[0017] The handle assembly 102 includes a hub that is attached to the proximal end 104 of the catheter 100 with an adhesive. The lumen of the hub (not shown) mates with the proximal port of the tubular body 106. The lumen of the hub is conically flared and acts as a "funnel" into the tubular body 106 of the catheter 100. The hub is made of a single polymeric material, such as nylon, polycarbonate, or a similar rigid material.

[0018] The inner liner 128 is a thin tube of a single material that serves as the exposed contact surface inside the central lumen 116 and runs the entire length of the catheter from the proximal to the distal end. The inner liner 128 may also be constructed of multiple closely stacked materials, referred to as "tie layers," as intermediate layers that act as a bonding bridge between the inner liner and the outer jacket. The inner liner is preferably made of a low friction material such as PTFE, polyolefins (including HDPE and LDPE), or blended polymeric materials (e.g., compounds of traditional polymers blended with lubricating additives), which may be created by extrusion or dip coating onto a mandrel. The wall thickness of the liner tube ranges from 0.0001 inches to 0.003 inches.

[0019] The tubular body 106 has a distal port 122 at the distal wavy tip 110 and a distal zone 112. The distal port 122 may have rounded, tapered or chamfered edges to make it less traumatic.

[0020] Distal zone 112, shown in more detail in Figures 5 and 6, has a helical coil 118 embedded in sidewall 114 of tubular body 106, with a distal end 120 of helical coil 118 spaced from a distal port 122 of tubular body 106. A tubular radiopaque marker 124 is embedded in sidewall 114 at a location between the distal end 120 of helical coil 118 and the distal port 122 of tubular body 106.

[0021] The helical coil 118 is created by wrapping one or more strands of wire around the inner liner 128 from the distal end 108 to the proximal end 104. The coil wire may be stainless steel, nitinol, or other suitable metal or polymer, depending on design considerations. The cross-sectional shape of the coil wire is round, rectangular, or oval. The cross-sectional dimensions of the coil wire may be 0.0003 inches to 0.009 inches.

[0022] The radiopaque marker 124 can be constructed from a variety of radiopaque materials, such as a platinum / iridium alloy, and can have a wall thickness of 0.0005 to 0.003 inches. The radiopaque marker 124 can be an intermittent or continuous band disposed on the distal end of the inner liner 128 and located at the distal end of the helical coil 118.

[0023] One or more reinforcing fibers 132 are embedded longitudinally in the sidewall 114 of the distal zone 112 and are bonded to a tubular radiopaque marker 124. The reinforcing fibers 132 are one or more strands of material oriented longitudinally along the catheter 100 and secured between the inner liner 128 and the helical coil 118. One end of the reinforcing fibers 132 is attached to the marker 124 near the distal end 108 of the catheter 100, and the reinforcing fibers 132 extend proximally along the catheter 100 for at least 10 cm, but may extend the entire length of the catheter depending on design considerations. The reinforcing fibers 132 may be monofilament or multifilament and are made from high mechanical strength materials, including but not limited to carbon fiber, liquid crystal polymer (LCP), carbon fiber, Kevlar, and other synthetic fibers. The diameter of the reinforcing fibers 132 may range from 0.0001 inches to 0.010 inches.

[0024] There may be one or more reinforcing fibers 132. Although Figures 5 and 6 show one reinforcing fiber 132, additional reinforcing fibers 132 may be provided in bundles or dispersed around the circumference of the tubular body 106. The reinforcing fibers 132 may extend longitudinally or may be slightly coiled along the length of the tubular body 106.

[0025] The outer jacket 130 is the exterior surface of the sidewall 114 and is constructed from a variety of polymeric materials, such as nylon, Pebax, polyether-based thermoplastic urethane (TPU), polyester-based TPU, polycarbonate-based TPU, and the like. Each outer jacket material begins as a single tube of material (i.e., an "extrusion" or "single lumen extrusion") that is placed over the inner liner 128, reinforcing fiber 132, helical coil 118, and markers 124 configuration. The stiffer polymeric material is placed at the proximal end 104 of the catheter 100, and the stiffer polymer is placed distally, such that the stiffness of the catheter decreases from the proximal end 104 to the distal end 108. Each jacket material is loaded end-to-end against the adjacent jacket material. Heat is then applied to the entire assembly using a processing aid such as FEP heat shrink, causing the jacket polymer to melt and flow, embedding into the helical coil 118 and markers 124, forming a single composite assembly. FEP heat shrink is a material that is placed throughout the catheter assembly during manufacturing, and when heated it heats up, clamps down, and holds all the catheter jacket material together as it flows.

[0026] In the embodiment of Figures 2-6, the distal port 122 includes a distal wavy tip 110 with a wavy edge that smoothly transitions between peaks 134 and valleys 136 in the circumferential direction to define a taper. There may be one peak 134 and one valley 136, or there may be up to five peaks 134 and five valleys 136. The distance between each peak 134 and valley 136 may be as little as 0.1 mm or as much as 3 mm. Figures 7A and 7B are two different isometric views of the distal port 122 of the catheter of Figure 3, showing these peaks 134 and valleys 136.

[0027] 8A-8C show how the distal wavy tip 110 aids the catheter 100 in passing over the protrusions L of the vessel bifurcation. Initial access to the occlusion site is typically achieved by using a guidewire G and / or microcatheter to navigate through the tortuous portion of the neurovasculature to the occluded artery. Once the guidewire and / or microcatheter is in place, the aspiration catheter 100 can be advanced over the guidewire and / or microcatheter with the guidewire and / or microcatheter within the central lumen 116 of the aspiration catheter 100. In FIG. 8A, the catheter 100 is advanced over the guidewire G. In FIG. 8B, the catheter 100 is advanced over the guidewire G. In FIG. 8B, the distal end 108 of the catheter 100 engages the protrusions L. The corrugations of the distal wavy tip 110 help alleviate this situation as they form a taper that helps prevent the distal wavy tip 110 from getting caught on the protrusions L. Depending on the orientation of the catheter 100 when it reaches the protrusion L, only a quarter turn of the catheter 100 may be required to clear the distal wavy tip 110 from the protrusion L, as shown in FIG. 8C, and the taper of the distal wavy tip 110 may aid in the passage of the catheter 100. In some circumstances, the peaks 134 and valleys 136 may allow the catheter 100 to easily pass over the protrusion L without having to rotate the catheter 100.

[0028] Thus, the shaped tip aspiration catheter 100 can be used by physicians during endovascular treatment of acute ischemic stroke. The catheter tip has wavy edges as opposed to traditional straight catheter tips. The catheter also has improved tensile strength due to the reinforcement at the distal end, without sacrificing maneuverability and flexibility.

[0029] The reinforcing fibers 132 extend along the distal direction and provide composite support much like rebar supports concrete. Tensile forces applied to the catheter are supported directly by the reinforcing fibers 132. Because the reinforcing fibers are thin fibers, they do not add significant stiffness to the bending profile of the distal end of the catheter, allowing the catheter to achieve the bending properties necessary to navigate the tortuous anatomy of the neurovasculature while also maintaining excellent tensile strength.

[0030] While the above description refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit of the invention, and it is intended by the appended claims to cover such modifications as fall within the true scope and spirit of the invention.

Claims

1. 1. A suction catheter comprising: an elongated flexible tubular body having a proximal end, a sidewall and a distal tip; a helical coil embedded in the sidewall and extending from the proximal end to a location proximally offset from the distal tip; a reinforcing fiber is embedded longitudinally in the sidewall beginning at a location proximally offset from the distal tip and extending proximally for at least 10 cm; An aspiration catheter, wherein the distal tip has a scalloped edge that transitions smoothly between peaks and valleys circumferentially to form a taper.

2. There are 1 to 5 peaks and 1 to 5 valleys. The catheter according to claim 1 .

3. 3. The catheter of claim 2, wherein the distance between each peak and each valley is in the range of 0.1 mm to 3 mm.

4. The catheter of claim 1 , wherein the helical coil has a distal end and further comprises a radiopaque marker band located at the distal end of the helical coil proximal to the distal tip.

5. The catheter of claim 4 , wherein one end of the reinforcing fiber is attached to the radiopaque marker band.

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